The present invention relates to a method for controlling an operation of a steam turbine provided with a turbine bypass system. More particularly, it is concerned with a starting method for a thermal power plant, which is effectively applicable to a transient state from an intermediate pressure starting operational condition to a steam supply condition in which the steam is supplied to a high pressure turbine.
In recent turbine plants provided with turbine bypass systems, a part of the steam from a boiler has been often introduced into a turbine bypass system, thereby enabling a rapid start/stop operation and suppressing any thermal stress generated in the turbine. Such a plant has a high pressure turbine bypass system for bypassing steam to be introduced into a high pressure turbine and an intermediate turbine bypass system for bypassing steam to be introduced into intermediate and low pressure turbines. The turbine plant is started as follows: